Pneumatic spring for vehicles.



site

PATENT OFFICE.

' JOSEF HOFMANN, OF BAUMAROCHE, SWITZERLAND.

PNEUMATIC SPRING FOR VlilI-IICI'JIXS.y

Specification of Letters Patent., f Paten'tdv'Aplv. 11, 1916.

Application led June 10, 1915. Serial No. 33,372.

, To all Iwhom/it may concern.'

Be it known that I, JosnF HOFMANN, a citizen of Switzerland, residing at Bau- Inaroche, Switzerland, have invented certain new and useful Improvements in Pneumatic Springs for Vehicles; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the saine, reference being had' to the accompanying drawings, and to letters or-tigures of reference marked thereon, which form a part of this specilication.

My invention relates to air springs in which there is a plunger element and a cylinder element with a pneumatic cushion which may or may not be inclosed in a sack between the'm. j

The object of the present invention is to provide mechanism whereby one of these elements moves at a greater speed than the other, and, preferably, in substantially changing ratio with respect to the other, whereby I obtain an' easy cushioning of the vehicle.y In order to'accomplish this I preferably construct the air spring in such a manner that one element is movable with respect to the Amember of the vehicle to.

which itis connected, and the other element is also'movable with respect to thegmember gree'and rate of compression.

of the vehicle to which it is connected, and:

both elements change their relative move- Y ment with respect to one another, and to this end Iproportion the lever arms of one eley ment to the other so as to control thede- In order that my invention may be more readily understood, reference will be had to the accompanying drawings which show' one of the many structures which I have used that embody myfinvention, andin which--- F i'gurel is a side elevation, partly in section; Fig. 2 is a plan view thereof. lFig'. 3.'

isa modification 'showing the plunger rod l:rigidly connected to its lever. vFig. 4 is a detail sectional view showing the joint con- A necting '-1 one of the levers' to' the vehicle. 'springg and' Fig. 5 illustrates a further modilicationin which 'the cylinder is curved .to conform to lthe path of the plunger.`

lReferring to Figs. 1 and 2, this device comprises a'bar vor member 1, which may beV of a'njjdesired length, and-which is arranged foricnnection' to `the' body 'orlframe Vof a" I nzotb'rsrveliiel'e. *The length of lthis bar will instance I prefer to,v

depend entirely upon the shape ofthe overhang of the body and the length of the leaf spring, and it will be cut to the length requlredlwhen .it :is placed on the car. The projecting end of this bar has an eye 2 provided -with a pivot having la grease cup 4. The lpivot 3 passes through the forked end 5 of an arm 6 connected to or forming ofa spherical member: or cylinder 7 inclosing a flexible diaphragm or pneumatic sack part 8 provided with a pneumatic inflating valve S, preferably i'n the. manner shown in Fig.

4, where the end of the lever 16 is provided with a ball seat a inl which seats the ballshaped end b of a pin c whereby universal [movement is vpermitted between the end of lever 16 'andthe shackle 17.

Thebell-crank lever 15 is also provided with-a pivot-point lf3-flor.the'endv of a plunger 20 thatcoperates with the cylinder member. 7 `-and acts-on,- the Isack or diaphragin. j e

It will be noted that the-sphericalcylinder element-7 in Closes a spherical pneumatic sack `8 acted upon by a plunger 420 of less diameter .than said element, which plunger passes through annopening'7-in the end of the element 7. I n 'this example'ithel plunger ismaintained centrally o fthevcylinder solely by the air pressure within the sack, which sack is caused by the air pressure to belly beneath andaround the plunger as the plunger enters the cylinder.l And in this particular y use a ball., and socket joint at the'pivot point 18 instead of a rockingv pivot, as it is easier to lubricate, and will retain the lubricant for a greater length of time. In order to cover' this joint and pro-4 tect it from dustv and dirt, I secure the upper plunger rod i9 by means of adfew Wraps of wire 22, andin a similar manner Wrap .the

lower vend ofv this tube withwire- 23 to connect it'to the exterior of the socket at `18.

from the spherical member or cylinder 7, whose forked end 12 end cfa tubular leather Washer 21v to the 0n the eye 2 of the bar 1 I provide a support 24 for a rubber or other buffer 25,. in

case an exceptionally great shock be imis imparted to the running gear of a vehicle,

causing the springs S to move upward, motion is imparted to the lever 15 to swing it on pivot 13, and at the same time tlie spherical cylinder member 7 moves upward about its pivot 3 but at -a less speed than the speed of the plunger 20, so that as both plunger and cylinder move upward, compression is produced within the sack 8. The did'erence in speed between the two movements, which determines the extent of compression', is dependent upon a lever arm a: extending between points 3 and 13 and composed of members 11, 7 and 6; lever arm y between ythe points 111 and 18, and a lever arm .e between the point 14 and the connection of arm 16 withthe shackle 17. The rate of compression may be altered by changing the relative lengths of these lever arms. When the spring S returns to normal position all the lever arms, m 3,/ and e swing downward -about the pivot point 5, the lever 15 moving in such manner as to cause theplunger `20 to move faster than the cylinder 7, and is assisted in moving out of the cylinder 7 by theforce of the compressed air in the sack 8.

It is obvious that the device may be inverted and the cylinder member 7 be connected to a running gear element and the lever 1.; to the body or frame of the vehicle.

It will be noted that as the spring S moves up there is a slower speed for the plunger 20, and this speed ratio will depend on the ratio of the eleetive lever arms y to s, as well as on the normal inclination of these lever arms, because they move about a pivot, and the leverage changes as they deviate from a horizontal. The speed of cylinder 7 is ,also dili'erent from that of spring S and of the plunger 2O and is slower than the speeds of both the spring and the plunger, and the speed ratio is dependent upon. the ratio of the effective lever arms y to e, their inclinations, and the inclination of a. The two speed ratios are different and constantly changing.

ln the two modifications shown in Figs. 3 a.: 4e, I have shown structures in which the joint between the plunger' piston 19 and bell-crank lever at 18 is omitted. The plunger rod 19a is slightly curved and rigidly connected to said bellfcrank' lever, thus dispensing with a joint that has to be lubricated.

In Fig. 5 the cylinder member 7b is not spherical, and its walls are curved so as to be concentric, or substantially concentric with the center about which the plunger rotates, namely the pivot point al' 13. The plunger stem 19 is similarly curved and carries the plunger 20L slightly tilted on the end of said stem, so as to give proper action on the sack Se, which is constructed to conform to the shape ol' the cylinder element 7".

I claim- 1. In a vehicle spring, the combination of two levers pivoted together, one of said levers pivotally connected to the vehicle frame and the other pivotallyconnected t0 a running gear element, aspring between the levers, said levers arranged for simultaneous movement in the'same direction at different speeds depending upon the variation of said spring and under all conditions of operation.

2. In a vehicle spring, the combination of two levers pivoted togethery at their ends, one of said levers also 'pivotally connected to the vehicle frame and the other to a running gear element, a spring between said two levers, said levers arranged to move simul taneously in the same direction with the vertical movements of the running gear element but at different rates of movement.

3. ln a vehicle spring, the combinationi with a pivoted spherical cylinder element, a

' 'plunger and plunger stem and a pneumatic sack between said element and plunger; of alever pivoted to said spherical cylinder element rigidly supporting the plunger stem and pivotally connected to a running gear element, the distance between the pivot point of said lever with said cylinder element, and the point of support for said plunger rod being `less than the distance between said pivot point and the point of connection with the running gear element.

4. A vehicle spring comprising two elements, a cylinder element and a plunger element, and a pneumatic sack between them, a lever pivotally connected to said cylinder element and supporting said plunger element, means for pivotally connecting the cylinder element to a vehicle part, and means for pivotally connecting said lever to a second vehicle part, said vehicle parts being movable relatively one to the other.

'5. A vehicle spring comprisingtwo .elements, a cylinder element and a plunger element, and a pneumatic sack between them, a lever pivotally connected to said cylinder element and supporting said plunger elei ment, means for pivotally connecting the cylinder element 'to a vehicle part, and means for pivotally connecting said lever to' a second vehicle part, said vehicle parts'- second vehicle part.

intensa dyirtvehicle spring comprising two elements,` a cylinder element and a plunger element, and a pneumatic sack between them, a lever pivotally connected -to said cylinder element, said lever rigidly connected to said plunger element, means for pivotally connecting the cylinder element to a vehicle part, and means for said lever to a second vehicle part, said vehicle parts being movable relatively one to the other, the distance on said levei` between its pivot point and the point of support of said plunger diering from the distance from said pivot point to the point of connection with said second vehicle part.

7. A vehicle spring comprising two elements, a curved cylinder element and a plunger element, and a pneumatic sack inclosed between them, a lever pivotally connected to said cylinder element, a curved plunger rod rigidly connecting said plunger and lever, means for pivotally connecting the cylinder element to a vehicle part and means for pivotally connecting said lever to another vehicle part movable relatively to the first vehicle part.

8. A vehicle spring comprisingtwo elements, a ,curved cylinder element and a plunger closed between them, nected to said cylinder element, a plunger rod rigidly connecting said plunger and lever, means for pivotally connecting the cylinder element to a vehicle part and means for pivotally connecting said lever to -another' vehicle part movable relatively to the first vehicle part. p

9.1In a vehicle spring, the combination with a cylinder'member and a cooperating piston member of an air spring; of means to movably connect "the cylindermember to a vehicle frame, and means to movably connect the piston member to a running gear element of the vehicle and to the cylinder element, said connections permitting si- -multaneous bodilymovement oi"- said elements with respect'to said frame and running gear element in the same direction but atdifferent rates. A A

l0. In a vehicle spring, the combination with two levers of diii'erent lengths pivotally connected together and forming an acute angle between them; of a spring included between the levers in said angle one oi said levers arranged for pivotal connection tothe vehicle body and the other lever arranged for pivotal connection with the running gear member of the vehicle.

ll. In a vehicle spring, the combination pivotally connecting element', and a pneumatic sackv in. a lever pivotal/ly conwith'two levers of diii'erent lengths pivoted together at an acute angle; of a spring included in the angle between said levers, said levers arranged for connection to the body' member and a running gear member of a vehicle, one of said levers having pivotal connection with one of said members, and the other lever having a connection permitting simultaneous movement in substantially rectangular directions. v

l2. In a vehicle spring-the combination with two levers of different lengths pivoted together at an acute angle'and arranged for connection to different members of a vehicle; of a spring included in the angle between said levers, one of said levers directly pivoted to one oi said vehicle membersand a shackle interposed between the other lever and another member of the vehicle.

13. In a vehicle spring, the combination with two levers of-diiilerent lengths pivotally connected together, an air spring included between the levers, one of said levers arranged for pivotal connection` to a vehicle body and the other to, a running gear element', and both levers moving in the same direction under all conditions of operation to vary the angle between them.

14. In a vehicle vspring the combination with two levers pivotallyconnected together at an angle to one another, one of saidlevers arranged to be pivoted 'to the vehicle frame and the other arranged to be pivoted to a running gear element of the vehicle, both ofl said levers arranged for simultaneous movement in the same direction at diferent rates under all conditions of operation, and a spring controlling said rate of movement of one lever-to and from the other according to the load during said simultaneous movement of the levers. 4 e

l5. In a vehicle spring the combination with two f' levers pivotally connected togeth'er, one of said levers arranged for pivotal 'connection to a vehicle body and the Aother arranged for connection to a running gear element, said points of connection being offset' from one another horizontally and both levers arranged for simultaneous movement in the same direction under all conditions of operation, and a Spring controlling the rate of movement of .one lever to and from the other according tothe load during said simultaneous movement of the levers.

In testimony that I claim the foregoing as my invention, I have signed my name in presence of two subscribing witnesses.

JOSEF HOFMANN. 

